Cameron Clark // Sr. // G
Clark tied his career high with 32 points on 10-of-18 shooting, and added three rebounds and a steal.

NORMAN, Okla. (AP) -- Thanks to a productive offense, Oklahoma had been able to somewhat overlook its defensive lapses as the Sooners raced to an 11-1 start this season.

But those problems now are starting to manifest themselves as losses. No. 18 Kansas shot 55 percent from the field in a 90-83 win over Oklahoma on Wednesday night.

The Sooners (12-3, 1-1 Big 12 Conference) have lost two of their last three games, surrendering 102 points to Louisiana Tech and 90 to Kansas. They entered Wednesday fourth in NCAA Division I in scoring at 87.3 points per game, but coach Lon Kruger said the defense must improve if they want to be among the Big 12's elite teams.

"This club has been pretty consistent on the offensive end," Kruger said. "They've done a good job of passing the ball and making plays for each other. Yet, we've got to figure out something different defensively, in terms of getting more stops."

It's a lesson not lost on Cameron Clark, who matched his career high with 32 points. But both times he's scored 32, the Sooners have lost, first to Michigan State, and now to the Jayhawks.

"It is very frustrating," Clark said. "We just have to go back to the drawing board. It all starts on defense. We just have to come together as a group and figured out what it is we are not doing and get better at it."

Freshman Wayne Selden Jr. went 5 of 10 from 3-point range and scored a career-high 24 points for Kansas (10-4, 1-0), which won its conference opener for the 23rd straight year, a streak that began with the 1991-92 season. Oklahoma, in January 1991, was the last team to beat the Jayhawks in a conference opener.

"It was the confidence my teammates and coaches have in me," Selden Jr. said of his successful game. "I was out there just playing and not thinking."

After a 5-0 start, the Jayhawks lost four of its next eight and were coming off a 61-57 loss to San Diego State on Sunday that ended their' 68-game home winning streak against nonconference foes.

Kansas has won 11 of the last 12 matchups with Oklahoma. The Jayhawks' latest win in the series could be especially important, considering the difficult stretch they face to start the Big 12 campaign. After Oklahoma, Kansas will host No. 25 Kansas State, visit No. 9 Iowa State, then host No. 11 Oklahoma State and No. 7 Baylor, all in succession.

"It's going to be a monster," Kansas coach Bill Self said. "Our league is great. When you think about OU and they go down and they win at Texas, and Texas wins at North Carolina. K-State is playing as well as anybody right now. Iowa State is obviously terrific, and Baylor. We've probably been, nonconference-wise, one of the bigger disappointments in the league, based on our preseason expectations. I think it's going to be a fabulous league."

The annual visit to Lloyd Noble Center by the Jayhawks -- who have won or shared nine straight Big 12 titles -- drew fans including country music star Toby Keith, Oklahoma City Thunder chairman Clay Bennett, and Thunder general manager Sam Presti.

Before the game, Oklahoma football player Sterling Shepard -- who scored two touchdowns in the Sooners' win over Alabama in the Sugar Bowl -- appeared in a video in which he said, "OK, basketball, we got our big win. Now it's time to get yours."

But the Sooners never really slowed Kansas and struggled to deal with the Jayhawks' size advantage inside. Kansas had a 36-22 edge in rebounding and didn't seem bothered by a subpar game by Andrew Wiggins. The star freshman went 2 of 9 from the field and scored only nine points, only the second time this season he failed to reach double digits.

"Kansas is awfully good and did a good job dictating a lot of it, for a majority of the minutes," Kruger said. "I thought our guys battled hard. There were maybe a couple of stretches in there when we didn't quite compete like we have to against a club like that to have a chance that we'd like to have."

Kansas led 50-44 at halftime and two free throws by Joel Embild made it 74-62 with 10:39 left.

Oklahoma stayed within striking distance and pulled within four points four times, the last time at 87-83 after a turnover by Wiggins and steal by Ryan Spangler led to a dunk by Buddy Hield with 39.9 seconds left.

Naadir Tharpe made two free throws moments later to push Kansas' lead to six points and, after Clark missed a 3 at the other end, Ellis made the back end of a two-shot free-throw opportunity to make it 90-83 with 29.2 seconds left. Wiggins blocked another 3-point attempt, by Frank Booker, and the Jayhawks eventually were able to run out the clock.

Tharpe scored 17 points for Kansas on 5-for-7 shooting. Hield had 18 points and eight rebounds for the Sooners, while Tyler Neal and Jordan Woodard had 10 points each. Woodard got all his scoring at the free-throw line, going 10 for 10 as Oklahoma made 29 of 36. Kansas went 24 for 30 from the line.

Kansas jumped to a 20-11 lead, but Oklahoma hung close thanks to 19-of-22 on free throws. With the score tied at 39 with 3:04 left before halftime, Wiggins was called for his second foul and Self protested, earning himself a technical foul. Oklahoma made all four subsequent free throws to go ahead.

Foul trouble forced Self to dig deep into his bench and freshman Conner Frankamp hit a 3-pointer and a 2 in the final 1:13 to give Kansas the six-point halftime lead.

Sooner Sports Powered by FOX Sports is a multi-platform network that provides distribution of 1,000+ hours of Sooner sports programming annually on a variety of FOX Sports outlets, including FOX Sports Oklahoma, FOX Sports Southwest, and FOX College Sports. Additionally, the partnership between the University of Oklahoma and FOX Sports includes a comprehensive digital component featuring extensive "all-access" content not televised on FOX Sports networks including live streaming, archived games, and exclusive materials.

OU inspires champions today and prepares leaders for tomorrow by enabling its student-athletes to achieve their highest academic, athletic and personal aspirations. The OU Athletics Department sponsors 21 varsity sports with more than 600 student-athletes and is completely self-supporting.

Sooner Sports Properties, LLC, is the multimedia rights holder for athletics at the University of Oklahoma. Sooner Sports Properties is a joint venture of Learfield Communications, Tyler Media, LLC and Griffin Television.